The inventors have developed an optical switch/switch activator for use in hazardous and non-hazardous environments, and more particularly to a float activated optical switch, where the switch activator includes a movable obstacle that can interrupt a beam of light (or pass a beam of light, depending on the orientation of the activator in the float body). See for instance, U.S. Pat. No. 7,234,830, hereby incorporated by reference. Improvements to the optical device are shown in PCT/US2007/70122, filed May 31, 2007, hereby incorporated by reference.
The earlier embodiments included two light guides (such as fiber optic cables), one connected to a source of light, the other connected to a light detector. Each light guide has a distal end positioned in an activator, where the two distal ends are separated by a gap but can be optically aligned. An optically opaque means to interrupt the beam of light is movable, and in one position, blocks the light path (optical path absent) and in another position, does not obstruct the light path (optical path present). Hence the device operates as a switch upon detection of the presence or absence of light by the light receiver. As disclosed in the PCT/US2007/70122 application, one embodiment has the moveable member or a means to interrupt (such as a reliable ball, or slidable cylinder or slug) positioned in an ampoule containing a fluid to reduce “switch flutter.” However, generally configurations shown are not sufficiently compact to create a compact activator for use in a small bodied switch, such as a small diameter float switch.